1. Field of the Invention
The present invention relates to a plug connector having a secondary locking device, and more particulary, to a plug connector having a secondary locking device which includes at least one leg, where the at least one leg fixes a locking arm of the plug connector in a final locked position in a socket, where at least one of the legs includes a locking arm with a step which is supported on a locking projection formed on a housing of the plug connector and which holds the secondary locking device in a pre-locked position, and further where the secondary locking device can be locked into the final locked position.
2. Description of Prior Developments
A plug connector typical of known plug connectors is illustrated in EP 1 006 621 A2. Plug connectors of this type find particular application as airbag restraint systems in automotive vehicles and are used for the connection of these airbag restraint systems to an ignition base. The ignition bases are located on, for example, the collapsible ring of the steering wheel or elsewhere, where the flat construction of the plug connector is important for reasons of space. It is a further essential requirement placed on such plug connectors that the insertion connection between the plug connector and the socket should not in any circumstances become loosened. It is the function of the secondary locking device to ensure that a plug and a socket shall not become loosened unintentionally.
Both EP-A-0 632 534 and WO 97/41623 describe a plug connector of a flat construction for connection to the ignition base of an airbag, where a secondary locking device prevents the loosening of the plug connector from the ignition base. The secondary locking devices can be unintentionally placed into the final locked position before the connector xe2x80x9chalvesxe2x80x9d are joined to one another, which prevents assembly.
A plug connector with a secondary locking device is also known from DE-C-197 28 448, where the secondary locking device is secured on the plug connector with locking legs, in order to prevent possible detachment. By means of introducing the secondary locking device into the appropriate socket, the locking legs prevent the locking arms of the plug connector from becoming loosened from the final locked position. If the secondary locking device of such a plug connector is placed in the pre-locked position, it can nevertheless happen that during transport or handling of the first connector parts, the secondary locking device becomes loosened from its pre-locked position and pressed into its final locked position, before the introduction of the plug connector into the socket has taken place. Through the locking legs which have been inserted, it is no longer possible to introduce the plug connector into the socket, i.e. into the ignition device, since the locking legs with their locking projections are wider than the slots into which they are to be inserted. Consequently, a device is needed to be able to loosen the secondary locking device manually.
EP 1 006 621 A2 describes a plug connector with a secondary locking device, wherein the secondary locking device can only be pressed into its final position through a part of the socket with an opening of a tong-shaped spring arm arrangement. Owing to the fact that the secondary locking device and the spring arms lie on different levels with respect to the longitudinal axis of the plug connector, the locking clamp can tilt both during the assembly of the locking clamp on a connector part and during the introduction of the plug connector into the socket, which can adversely affect the assembly of the plug connector parts.
It is an objective of the present invention to develop a plug connector as described above in such a way that the unintentional pressing of the secondary locking device into its final locked position is impossible before the two plug connector xe2x80x9chalvesxe2x80x9d have been joined together, without adversely affecting the joining process itself.
Thus, in accordance with the features of the present invention there is described a plug connector having a secondary locking device which includes at least one leg, where the at least one leg fixes a locking arm of the plug connector in a final locked position in a socket, where at least one of the legs includes a locking arm with a step which is supported on a locking projection formed on a housing of the plug connector and which holds the secondary locking device in a pre-locked position. Further wherein the secondary locking device can be locked into the final locked position. The invention is characterized by the secondary locking device including two spring arms, each of the arms having a step and a projection which are arranged symmetrically to a longitudinal axis of the plug connector, whereby during the process of insertion of the plug connector into the socket, the spring arms are deflected by the locking projections so that the step of the spring arms is lifted from the locking projections and the secondary locking device is thereby released.
In one preferred embodiment of the present invention, the spring arm has on its insertion end a projection, through which during the insertion of the plug connector into the socket, the spring arm is deflected in such a way that the step of the spring arm is lifted from the locking projection and the secondary locking device is released. By means of this form of the spring arm, the latter is bent during the process of insertion of the plug connector into its socket when the projection reaches the socket, whereby the step is loosened from the locking projection. Preferably, the locking projection is wedge-shaped where, during the introduction of the plug connector into its socket, the wedge-shaped section reaches a face of the socket opposite the plug connector. As the introduction of the plug connector into its socket proceeds, the spring arm is introduced into an opening of the socket, which may, for example, be the opening into which the insertion face of the plug connector is inserted.
In another preferred embodiment of the present invention, the free ends of the legs are supported on the free end of the locking arms during the introduction of the secondary locking device into the plug connector, whereby the introduction of the secondary locking device into the final locked position is prevented, until the locking arms snap into the recesses provided for the locking of the plug connector into its socket, whereby the locking arms vacate the insertion path of the legs and the secondary locking device becomes lockable into the final locked position. This invention-related geometry also prevents the secondary locking device from being able to be placed in its final locked position. Only when the locking shoulders of the locking arms are locked into the recesses provided for that purpose in the socket, are the pre-tensioned locking arms pressed outwards and only then an insertion of the secondary locking device becomes possible. This leads to two conditions for the insertion of the secondary locking device into its final locked position. Firstly, the shoulder of the spring arm must be lifted from the locking projection formed on the housing of the plug connector and secondly, the plug connector must have become finally locked into the socket, until an insertion of the secondary locking device becomes possible. This makes it easy for the operative to ascertain from the outside, whether the plug connector and the socket are correctly joined. If the secondary locking device can be brought into its final locked position, then the joining of the plug connector and its socket has been successful.
In still another preferred embodiment of the present invention, the locking arms are formed on an insertion face on the underside of the housing, whereby the free ends of the locking arms are bent against the direction of insertion. In this way, it is possible for the rear face of the locking arms is able to reach the lower end of the leg, whereby the insertion of the secondary locking device is prevented until the locking arms have vacated the insertion path by swinging outwards, when a complete joining of the two plug connector portions has taken place.